Antennas for wireless voice and/or data communications typically include an array of radiating elements connected by one or more feed networks. Many base station antennas include a plurality of radiating elements in a linear array. Various attributes of the antenna array, such as beam elevation angle, beam azimuth angle, and half power beam width may be adjusted by electrical-mechanical controllers. See, for example, U.S. Pat. Nos. 6,573,875 and 6,603,436, both of which are incorporated by reference.
For example, with respect to U.S. Pat. No. 6,573,875, a plurality of radiating elements may be provided in an approximately vertical alignment. A feed network may be provided to supply each of the radiating elements with a signal. The phase angle of the signals provided to the radiating elements may be adjusted to cause a radiated beam angle produced by the antenna array to tilt up or down from a nominal or default beam angle. The phase angles may be adjusted by operating electromechanical components, such as phase shifter. Phase shifters may be employed to adjust beam downtilt and/or beam azimuth angle, and/or to adjust power division, and thereby adjust beam width. In one example, phase shifters may be coupled to an actuator, allowing remote control of the adjustment of the phase shifter.
Another example of electrical downtilt control involves a phase shifting technique called “power shifting.” An example of this is provided in U.S. Pat. No. 6,864,837, which is incorporated by reference. Briefly, an RF signal is applied to a variable power divider, which is then applied to a Butler matrix. The output of the Butler matrix has four ports having different phase angles depending, which, when applied to radiating elements, steer an output beam of the antenna array up or down.
Multiband antennas are also known. A conventional multiband antenna may include different radiating elements for each of the bands. See, for example, U.S. Pat. No. 6,295,028, U.S. Pat. No. 6,333,720, U.S. Pat. No. 7,238,101 and U.S. Pat. No. 7,405,710, the disclosures of which are incorporated by reference. Each set of radiating elements typically has its own feed network.